Details

This is an old-fashioned cut flower and still one of the best, giving gorgeous bouquets of frilly pastel blooms. Centaurea cyanus is an upright annual to 75cm, with simple or slightly lobed leaves and solitary flower-heads across that bloom in late spring and summer.
Cornflower ‘Polka Dot’ is a delightful mix of semi-dwarf bachelor's buttons, growing to just 30 to 45cm (12 to 18in) - half the size of a regular Bachelors Button. It blooms earlier than many other varieties. The blooms appear in a wonderful range of shades and colours, from white to pale pink and blues, through to purples and plums, some are bi-colours.

Cornflowers thrive in poor soil and are drought tolerant. Very easy to grow, this hardy annual can be sown in spring or in autumn, they are ideal for beds and borders and can also be grown in containers. They make a wonderful addition to any cutting garden and last well in the vase. They also make a good dried flower.

Sowing: Sow in Spring or Autumn.
Sow in spring, March to May directly where they are to flower for flowers July to September, or sow during Autumn, August to September to flower from June the following year.

Sowing Direct :
Sow thinly, 3mm (1/8in) deep in drills 30cm (12in) apart in well-cultivated soil which has been raked to a fine tilth. Water ground regularly, especially in dry periods.
When large enough to handle, thin out seedlings to 15cm (6in) apart

Sowing Indoors:
Sow in pots or trays of moist seed compost and cover with a very fine sprinkling of compost or vermiculite. After sowing, do not exclude light as this helps germination. Keep at 15 to 20°C (59 to 68°F). Keep the surface of the compost moist but not waterlogged. Germination will usually take 14 to 21 days.
When they are large enough to handle, transplant the seedlings into 7cm (3in) pots or trays. Overwinter plants in cool, light, frost-free conditions before planting out the following spring, or grow on as greenhouse pot plants.

Cultivation:
This fully hardy plant requires a sunny site, growing in most well-drained soil types, even poor soil.
Do not over fertilise because this will lead to excessive leaf growth at the expense of blossoms. Cornflowers bloom more when crowded.
The wiry plants may need some discreet support, and deadheading helps to prolong the flowering season.

Other Uses:
Cornflowers are prized historically for their blue pigment. Cornflowers are often used as an ingredient in tea and is famous in the Lady Grey blend of Twinings.

Nomenclature:
Once upon a time anything that grew and bloomed in a grain field was considered a 'cornflower.' As time passed, that moniker stuck to Centaurea cyanus in particular, all the other flowers left to find their own names.
Bachelor's-buttons, as you might suspect from the Latin genus and species, have a bit of folklore under its belt. Cyanus was a youth in Greek legend who worshipped Chloris (or Flora), and spent every waking hour gathering flowers for her altar. (Today we call this a stalker.) When he died, the goddess gave his name to the plant, though some believed she turned him into the plant.
Centaurea comes to us from the Centaur Chiron, who cured a festering wound that was made with an arrow dipped in the Hydra's blood. The wound was cured by covering it with the flowers of this plant, which now bears his name as its genus name. This also gave the plant its reputation for great healing properties.